Mutation, quasispecies and lethal mutagenesis

摘要

Viral pathogenesis is not alien to the evolutionary history of a virus. Picornaviruses, simply by the fact of sharing a phylogenetic position, need not be associated with similar diseases, reflecting that the nature of the interactions with their host organisms may depend in a subtle manner on minimal genetic change of the virus. Picornaviruses have served to establish core concepts in the understanding of viruses as mutated collectivities and in establishing the relevance of quasispecies for viral pathogenesis. The adaptive potential of RNA viruses is also manifested in the response to selective agents administered to inhibit their replication. High mutation rates result in the almost-systematic selection of viral mutants resistant to antiviral inhibitors, either because resistant mutants are present in mutant spectra or because they are rapidly generated during viral replication. The participation of interfering genomes in virus extinction constitutes the basis of the lethal defection model of virus extinction by enhanced mutagenesis. The initial experiments to test the validity for RNA viruses of the error threshold concept consisted of documenting an adverse effect on viral infectivity as a result of increasing the mutation rate of poliovirus (PV) and vesicular stomatitis virus by chemical mutagens and base and nucleoside analogues added during viral RNA replication. Genetic modifications upon extensive passage of FMDV in BHK- 21 cells included genomes with internal in-frame deletions that were infectious by complementation in the absence of standard, wildtype genomes.